Evolution of a third generation (3G) system is in progress to provide a higher data rate, lower latency, and support of multiple radio access technologies (RATs). The main features of the evolved 3G system include an enhanced air interface to handle higher data rates with more efficiency, optimization of conventional procedures to reduce the number of signaling procedures and reduce setup delay, and network design to permit interconnection and interoperation of any air interface, such as global standards for mobile communication (GSM), general packet radio services (GPRS), wideband code division multiple access (WCDMA), CDMA2000, IEEE 802.xx, or the like.
FIG. 1 shows a conventional GPRS access interface and reference points. A mobile station (MS) 102, which includes a terminal equipment (TE) 104 and a mobile terminal (MT) 106, is attached to one of a plurality of GPRS packet domain networks 108a, 108b, which is further connected to a packet data network 110. The GPRS packet domain networks 108a, 108b perform a network access control function, a packet routing and transfer function, a mobility management function, a logical link management function, a radio resource management function, a network management function, or the like.
The network access control function includes registration, authentication and authorisation, admission control, message screening, packet formats adaptation, charging data collection, operator determined barring, or the like. The packet routing and transfer function includes relay, routing, address translation and mapping, encapsulation, tunnelling, compression, ciphering, domain name server, or the like. The logical link management function includes establishment, maintenance and release of a session.
FIGS. 2A and 2B show conventional state machines for mobility management (MM) of an MS and a serving GRPS support node (SGSN) in an Iu mode. The MS and the SGSN may be in one of a packet mobility management (PMM)-detached state, a PMM-connected state and a PMM-idle state. In the PMM-detached state, there is no communication between the MS and the SGSN. In order to establish MM contexts in the MS and the SGSN, the MS performs a GPRS attach procedure. Upon GPRS attach, the state changes to the PMM-connected state, and a packet switching (PS) signaling connection is established between the MS and the SGSN. A PS signaling connection release changes the state to the PMM-idle state. GPRS detach, PS attach reject or routing area update (RAU) reject causes the state to change to the PMM-detached state. In the PMM-idle and PMM-connected state, the session management (SM) state may be active or inactive.
FIGS. 3A, 3B and 3C, taken together, are a signaling diagram of an attach procedure 300 in a conventional GPRS system. As shown in FIG. 3A, an MS 302 initiates the attach procedure 300 by the transmission of an attach request message to a new SGSN 306 (step 322). The attach request message includes an international mobile subscriber identity (IMSI) (alternatively, a packet-temporary mobile subscriber identity (P-TMSI) and an old routing area identity (RAI)), an attach type, or the like.
If the MS 302 identifies itself with the P-TMSI, the new SGSN 306 derives an old SGSN address from the RAI to request IMSI information of the MS 302 (step 324). The new SGSN 306 sends an identification request message to an old SGSN 308 (step 326). The identification request message includes a P-TMSI, an old RAI, old P-TMSI signature, or the like. The old SGSN 308 checks the P-TMSI against record and sends an identification response message with the IMSI of the MS 302 to the new SGSN 306 (steps 328, 330). If the MS 302 is known in the old SGSN 308, the old SGSN 308 responds with an identification response message including the IMSI, authentication triplets or authentication quintets. If the MS 302 is not known in the old SGSN 308 or the old P-TMSI does not match the value stored in the old SGSN 308, the old SGSN 308 responds with an appropriate error cause in the identification response message at step 330.
If the MS 302 is unknown in the old SGSN 308, the new SGSN 306 sends an identity (ID) request (ID Type=IMSI) to the MS 302 (step 334). The MS 302 responds with an ID response including the IMSI of the MS 302 (step 336).
If no MM context for the MS exists anywhere in the network, an authentication procedure is performed by the MS 302, the new SGSN 306 and a home location register (HLR) 314 (step 338).
Referring to FIG. 3B, based on operator configuration, an international mobile equipment identity (IMEI) checking procedure may optionally be performed by the MS 302, the new SGSN 306 and an equipment identity register (EIR) 310 (step 340). If the SGSN number has changed since the last GPRS detach, or if it is the very first attach, the new SGSN 306 updates the HLR 314 by sending an update location message to the HLR 314 (step 342). The update location message includes an SGSN number, an SGSN address, the IMSI, or the like.
The HLR 316 compares the SGSN number with records and sends a cancel location message (including IMSI, cancellation type) to the old SGSN 308 (steps 344, 346). The old SGSN 308 acknowledges with a cancel location acknowledgement (ACK) (step 348). The HLR 314 sends an insert subscriber data message including the IMSI and GPRS subscription data to the new SGSN 306 (step 350).
The new SGSN 306 checks if the MS 302 is not allowed in the new routing area (RA) (step 352). If due to regional subscription restrictions or access restrictions the MS 302 is not allowed to attach in the RA, the new SGSN 306 rejects the attach request with an appropriate cause, and may return an insert subscriber data ACK (including the IMSI, an SGSN area restricted message) to the HLR 314 (steps 354). If the subscription checking fails for other reasons, the new SGSN 306 also rejects the attach request with an appropriate cause and returns an insert subscriber data ACK (including the IMSI and a cause) to the HLR 314. If all checks are successful, the new SGSN 306 constructs an MM context for the MS 302 and returns an insert subscriber data ACK (including the IMSI) to the HLR 314 (steps 356,358). The HLR 314 updates the MM context and sends an update location ACK to the new SGSN 306 (steps 360, 362).
Referring to FIG. 3C, if the attach type indicated in the attach request indicates a combined GPRS/IMSI attach, a visitor location register (VLR) should be updated. The new SGSN 306 sends a location update request to a new VLR 312 (step 364). The location update request includes a new LAI, the IMSI, an SGSN number, a location update type, or the like.
The new VLR 312 creates an association with the new SGSN 306 by storing the SGSN number. If the location area (LA) update is inter-mobile switching center (MSC), the new VLR 312 sends an update location message (including the IMSI and a new VLR) to the HLR 314 (step 366). The HLR 314 sends a cancel location message to an old VLR 316 (step 368). The old VLR 316 acknowledges with a cancel location ACK (step 370).
The HLR 314 sends an insert subscriber data message (including the IMSI and subscriber data) to the new VLR 312 (step 372). The new VLR 312 acknowledges with an insert subscriber data ACK (step 374). After finishing the inter-MSC location update procedures, the HLR 314 responds with an update location ACK to the new VLR 312 (step 376). The new VLR 312 responds with a location update accept message (including VLR TMSI) to the new SGSN 306 (step 378).
The new SGSN 306 sends an attach accept message to the MS 302 (step 380). The attach accept message includes a P-TMSI, a VLR TMSI, P-TMSI signature, and radio priority SMS. The MS 302 then returns an attach complete message to the new SGSN 306 and the new SGSN 306 sends a TMSI reallocation complete message to the new VLR 312 (steps 382, 384).
FIG. 4 is a diagram of a conventional state machine for SM. A GPRS subscription contains the subscription of one or more packet data protocol (PDP) addresses. Each PDP address is an element of a PDP context. The PDP state indicates whether data transfer is enabled for that PDP address or not. The PDP state is moved from an inactive state to an active state when PDP context is activated. The active state is changed to the inactive state when the deactivation procedure is initiated, or when the MM state changes to the PMM-idle state or PMM-detached state.
In the inactive state, the data service for a certain PDP address of the MS is not activated and the PDP context contains no routing or mapping information to process PDP protocol data units (PDUs) related to that PDP address. In the active state, the PDP context for the PDP address in use is activated in the MS, SGSN and gateway GPRS support node (GGSN). The PDP context contains mapping and routing information for transferring PDP PDUs for that particular PDP address between the MS and the GGSN. The active state is permitted only when the MM state of the MS is PMM-idle state or PMM-connected state.
FIG. 5 is a flow diagram of a conventional PDP context activation procedure 500. The MS 302 sends an activate PDP context request message to an SGSN 306 (step 502). The activate PDP context request message includes a PDP type, a PDP address, an access point name (APN), quality of service (QoS) requested, protocol configuration options, or the like. The SGSN 306 validates the activate PDP context request, selects an APN and maps the APN to a GGSN 310 (step 504).
The SGSN 306 sends a create PDP context request message to the GGSN 310 (step 506). The create PDP contest request message includes a PDP type, a PDP address, an APN, QoS negotiated, a TEID, charging characteristics, or the like. The GGSN 310 creates a new entry in its PDP context table and returns a create PDP context response to the SGSN 306 (step 508). The create PDP context response message includes a TEID, a PDP address, protocol configuration options, QoS negotiated, charging ID, or the like.
Radio access bearer (RAB) setup is performed among the MS 302, the RAN 304 and the SGSN 306 (step 510). In Iu mode and if basic service set (BSS) trace is activated, the SGSN 306 may send an invoke trace message to the RAN 304 (step 512). The SGSN 306 may inform the GGSN 310 about the downgraded QoS attributes by sending an update PDP context request (step 514). The GGSN 310 confirms the new QoS attributes by sending an update PDP context response to the SGSN 306 (step 516).
The SGSN 306 inserts the GGSN address in its PDP context (step 518). If the MS 302 has requested a dynamic address, the PDP address received from the GGSN 310 is inserted in the PDP context. The SGSN 306 selects radio priority and packet flow ID based on QoS negotiated, and returns an activate PDP context accept message to the MS 302 (step 520). The activate PDP context accept message includes a PDP type, a PDP address, a transaction identifier (TI), QoS negotiated, radio priority, a packet flow ID, protocol configuration options, or the like. If the MS 302 indicated in the MS network capability it does not support BSS packet flow procedures, the SGSN 306 then shall not include the packet flow ID.